Basiceros scambognathus (Brown, 1949) n. comb., with the first worker and male descriptions, and a...

Museu de Zoologia, Universidade de São Paulo, Caixa Postal 42.494, CEP 04218‑970, São Paulo, SP, Brasil. E‑mails: a: [email protected]; b: [email protected]; c: [email protected]

1.

Volume 47(2):31-42, 2007

Basiceros scamBognathus (Brown, 1949) n. comB., with the first worker and male descriptions, and a revised generic

diagnosis (hymenoptera: formicidae: myrmicinae)

rodrigo machado feitosa1a carlos roBerto ferreira Brandão1B

Bodo hasso dietz1c

AbstrAct

We propose the synonymy of the monotypic neotropical myrmicine (Basicerotini) ant genus Creight‑onidris Brown with Basiceros Schulz, and describe for the first time the worker and male of B. scam‑bognathus n. comb., known thus far only by alate gynes. We also provide information on the distribu-tion of this species, a revised diagnosis for Basiceros, and a revised key to workers and gynes of this genus. The few known data on the biology of B. scambognathus are summarized.

Keywords: ants, Basicerotini, Creightonidris, Basiceros, key, synonymy, worker and male description.

(1960) also studied basicerotine material from Botel Tobago Island just off southern Formosa.

All basicerotine species come from predomi‑nantly mesic habitats, particularly from the leaf‑litter and superficial soil layers. Colonies are monogynous and relatively small, nesting in natural cavities, fall‑en twigs, empty dry fruits or rotten wood. Workers forage alone, mostly preying upon a wide range of soft bodied arthropods and their larvae (Hölldobler & Wilson, 1990). According to Brown (1974), “the adults move very slowly, and they feign death for long periods when disturbed, rivaling the attine Apterostig-ma in their ability to escape detection by this means in the forest gloom”. Weber (1950) recorded a worker of B. singularis carrying a dead termite in Guyana, and Brown (1974) found headless termites inside a nest

IntroductIon

The myrmicine ant tribe Basicerotini Brown in‑cludes seven nominal genera: Basiceros, Creightonidris, Eurhopalothrix, Octostruma, Protalaridris, Rhopalothrix, and Talaridis (Bolton, 2003). Brown (1949) recognized these genera as distinct from Dacetini; although these ants are similar in appearance due to convergence in characters held in common by members of both tribes (Brown & Kempf, 1960). Basicerotini has a strongly disjunct distribution, occurring in the New World (primarily Neotropical, with one species in Florida, USA) and in the Melanesian region (Australia, New Caledonia, Fiji, Samoa, Papua New Guinea, Solomon Islands Borneo, Malaysia, Indonesia, Singapore, Pa‑lau, Brunei, and the Philippines). Brown & Kempf

32 Feitosa, r.M. et al.: the worKer and Male castes oF Basiceros scamBognathus n. coMb.

of the same species in Diamantino, Mato Grosso, Brazil.

Baroni Urbani & De Andrade (1994) synony‑mized Dacetini as well as Phalacromyrmecini under Basicerotini, and synonymized all subtribal names ac‑cepted at the time. Bolton (1995a) revived Basicero‑tini from synonymy of the then so‑called Dacetonini and, in 1998, listed and commented the apomorphies of the Dacetini tribe group and its components, including the Basicerotini, which he considers as monophyletic.

Creightonidris is a monotypic basicerotine ge‑nus established by Brown (1949), based on a single alate gyne. In the revision of Basicerotini (Brown & Kempf, 1960), Creightonidris was recognized as a valid genus by the authors based mainly on its very special‑ized and aberrant mandibles, although they also rec‑ognized its close relation to Basiceros. The only species of the genus, C. scambognatha, has been known up to now from very few alate gynes and a single not yet formally described worker (Castilho et al., in press), captured exclusively in central‑north Brazil (Delabie, 2000) and south Venezuela (Lattke, 1991).

However, since the original description by Brown (1949) and the revision by Brown & Kempf (1960), several undescribed males of C. scambognatha from different localities have accumulated in the Mu‑seu de Zoologia da USP ant collection (MZSP), from which two series also have some alate gynes. It was possible to associate males and gynes by comparing mainly the wing venation, the sculpture pattern, and considering the information on the specimens labels (Dietz, 2004).

Dietz (2004), in his Basicerotini revision, sug‑gested the synonymy of Creightonidris with Basiceros, based on the comparison of the then undescribed C. scambognatha males with males of Basiceros species, especially as to the wing venation pattern and on the analysis of other characters variation among basicer‑otine ants. Our study of the second C. scambognatha worker ever found and here presented, corroborates Dietz´s proposal.

Virtually nothing is known about the biology of C. scambognatha. The only dealate gyne, collected in southern Goiás, Brazil, and maintained in artifi‑cial conditions, died some weeks after confinement in the laboratory of the MZSP (Brandão, unpubl. observations). More recently (June, 2006), a party, including one of us (RMF), collected the second worker of this species in the leaf litter of a semi‑deciduous lowland forest in the Estreito county, Ma‑ranhão state (near the border with Tocantins state) in central Brazil.

The aim of this work is to establish formally the synonymy of Creightonidris with Basiceros, and add new information on its diagnosis. We take this opportunity to describe for the first time the male and the worker castes of Basiceros scambognathus and to record new in‑formation regarding the distribution and biology of this species.

MAterIAl And Methods

Although Creightonidris scambognatha has been considered one of the rarest Neotropical ant species, we were able to find specimens in different collec‑tions, as follows:

ANIC: Australian National Insect Collection, CSIRO, Canberra, Australia.

INPA: Instituto Nacional de Pesquisas da Amazô‑nia, Manaus, Amazonas, Brazil.

MCZC: Museum of Comparative Zoology, Har‑vard University, Cambridge, Massachusetts, USA.

MZSP: Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil.

PSWC: Philip S. Ward Personal Collection, Univer‑sity of California, Davis, California, USA.

Morphological terms follow Brown & Kempf (1960) and Dietz (2004). Reproductive females are here called “gynes”, as suggested by De Andrade & Baroni Urbani (1999). The measurements and in‑dexes adopted are: TL total length, HL head length, HW head width, ML mandible length, SL scape length, CW Weber’s length, HFL hind femur length, CI cephalic index (HW x 100/HL), and SI scape in‑dex (SL x 100/HW). All measurements are given in mm.

Photographs taken under the MZSP scanning electron microscope (SEM) (LEO 440®) were used to record morphological details of a gyne and a male of B. scambognathus. The specimens were pre‑viously cleaned in acetone, critical‑point dried in a Balzer (Bal‑Tec® CPD 030), and sputtered over with gold (Bal‑Tec® SCD 050). After that, the specimens were mounted on the tip of metallic tri‑angles using silver glue and then fixated on stubs for the electron microscopy. The images were obtained under several magnifications, accord‑ing to the size of the specimen and/or structure observed. Finally, the images were edited (Adobe PhotoShop 7.0®) to enhance some brightness and contrast details.

PaP. avuls Zool. 47(2), 2007 33

Geographic coordinates were obtained from ENCARTA World Atlas® and the distribution map generated by ArcView 3.2 GIS®.

results

Basiceros schulz, 1906

Meranoplus (in part) Fr. Smith 1858:195.Ceratobasis Fr. Smith 1860:78 (junior homonym of

Ceratobasis Lacordaire, 1848:362 Coleoptera).Basiceros Schulz 1906:156 (replacement name for Cera-

tobasis; Meranoplus singularis type species by mono‑typy); Wheeler & Wheeler, 1954:112‑113 (larvae description); Brown & Kempf, 1960:171‑172 (worker and gyne diagnosis); Brown, 1974:132 (worker, gyne and larvae diagnosis, male de‑scription; distribution and biology); Bolton, 2003:183‑184 (taxonomic history).

Aspididris Weber, 1950:3 (A. militaris type species by monotypy), junior synonym of Basiceros Schulz: Brown, 1974:132.

Creightonidris Brown 1949:89 (C. scambognatha type spe‑cies by monotypy), new synonym.

Worker: Size relatively medium (TL between 4,9 and 8,7 mm). Reddish to dark‑brown in color. Integument thick and in general densely sculptured; foveolate over head disc, mesosoma with conspicuous deep to shal‑lowly set punctuation, densely punctate over most or all the gaster. Pilosity conspicuous and bizarre; sub‑decumbent hairs abundant, spatulate, squamiform or plumose; erect abundant or sparse hairs clavate or stout and truncate. Labrum with fine sensorial hairs.

Head trapezoidal, triangular or rounded posteri‑orly; posterior and lateral head borders always visible and clearly distinct, and either rounded or crested, or else combined into curving, continuous or near con‑tinuous crest around posterior margin of head. Dorsal surface of head flattened to depressed, slightly convex in some species. Mandibles sub‑porrect, triangular to subtriangular, with straight, opposable, multidenticu‑late masticatory borders; apical portion from straight to strongly bent ventrally; basal portion flat and smooth to moderately convex and sculptured in frontal view; blade narrowed near insertion, the resulting peduncle either partly exposed or entirely hidden beneath clypeus, in‑terspace between basal mandibular margin and anterior clypeal border present to absent in varying degrees. Eyes relatively well developed (ocular index ca 11). Antennal scape flattened, broad, and lobate at the basal portion; funiculus moderately clavate with 11 segments.

Mesosoma usually robust. Metanotal groove present. Propodeal teeth always triangular in lateral view, lamelliform, short, more or less acute, and con‑nected to each other by a transverse carina. Petiole pedunculate and usually with ventral carina bearing one or more teeth. Gastric dorsum with a median lon‑gitudinal strip slightly impressed or devoid of pilosity. According to Brown (1974) Basiceros has 5 Malpighian tubules.

Gyne: Like conspecific worker, with modifications ex‑pected for myrmicine gynes. Ocelli present. Prescutum usually longer than wide; notauli from almost indis‑tinct to shallowly depressed; parapsidial lines shinning and usually indistinct from surrounding sculpture, deep to shallow parapsides; prescutellum with central area indistinct, scuto‑scutellar sulcus from deeply to shallowly impressed or almost indistinct, with trans‑versal rugulae varying in number; lateral wing of pres‑cutellum projecting postero‑ventrally as a more or less developed hook‑like structure; scutellum square‑like or semicircular, with its posterior half always sloped down, posterior border concave. Metanotum median elevation bears a pair of specialized setae. Forewing with distinct and strongly colored stigma; longitudinal veins Sc+R, SR, M+Cu, and A present; SR extends distally beyond stigma as tubular vein for most of its length; M and Cu also extend distally, initially as tubu‑lar veins, then as spectral veins almost reaching distal wing border; cross vein M+Cu either absent, as an appendix of M or complete, thus forming open or closed M1 cells; anal vein connected to M+Cu near branching point, either before, at or after. Hind wing with Sc+R extending shortly beyond point where they connect to M, which extends as tubular vein as much as Sc+R and then continues as spectral vein to wing distal border; basally M+Cu does not continue as tubular vein beyond junction with Anal vein, which is connected halfway to M and Cu branching point; tubular part of Cu is a mere stub, continuing as spec‑tral vein distally; 5 sub‑median hamuli present.

Male (modified from Brown, 1974): Slightly smaller and more slender than conspecific gynes. Color black with appendages somewhat lighter. Integument very finely and densely punctate, opaque or nearly so, including legs, mandibles and antennae. Head vertex with over‑lying loose rugulae, especially behind compound eyes and around ocellar triangle; loose rugulation also on alitrunk, especially on posterior half of mesonotum and sides of propodeum. In some species parts of mesopleura smooth and shining, or rugulose. Pilos‑ity composed of fine tapered hairs, golden brown in


color, mostly erect or suberect on body, but also ap‑pressed on gaster and clypeus in some species; man‑dible, antennae and leg hairs becoming shorter, more abundant and decumbent passing from base to apex of these appendages.

Head broadest across large bulging eyes (situ‑ated at or slightly in front of head mid‑length) rather suddenly narrowed in front of eyes and tapering mod‑erately anterad; median vertex and ocelli prominent. Mandibles relatively developed, subtriangular, with curved outer borders converging rapidly in apical half; gently down curved and weakly convex dorsal faces. Masticatory borders bearing 8‑12 serial teeth. Mandibles petiolate or not, when closed leaving or not a space between anterior border of clypeus and mandibles; in general labrum shape as in conspecific workers. Clypeus broad, truncate or rounded in front, extending to level of frontal lobes; its antero‑lateral lobes concave, free margin with thin, sharp, yellowish edge, transverse or concave in front and rounded‑di‑vergent on sides. Frontal area variably distinct, semi‑circular or transverse, more or less impressed; rugose or carinate in the middle, and relatively well delimited behind by an arched carina or rugulae that tend to connect the two frontal lobes. Frontal lobes promi‑nent and projecting forward, laterad and dorsad, their free margins rounded sharply in front and broadly lat‑erad, antennal insertions located on their ventral fac‑es. Lateral bases of lobes continued laterad as sharply raised arching carinae running close near the eye on each side, and then curving forward to bound deeply excavated, subreniform antennal scrobes bounded in front by cariniform posterior borders of lateral wings of clypeus. Posterior vertex bordered along cervical limit by lamelliform margin bearing short longitudi‑nal costulae; space between this and posterior ocelli either steep or gradual, depending on whether head is much drawn out behind or not. A continuous, or nearly continuous, sharp but irregular, ventro‑lateral carina extends from the posterior corner of head to mandibular insertion, bordering subrectangular area of cheek between eye and mandibular insertion, and bounded mesad by carinate outer scrobe margin. Antennae long and slender with 13 segments. Scape very short, only about twice as long as broad, its base oblique, with the more acutely rounded angle on out‑side, and obtuse angle inside, tapered towards trun‑cate apex; a little thicker than remaining segments. Antennal segments 2 and 3 (counting from base) only about half as long as scape; succeeding segments all much longer than broad; apical segment longest; an‑tennal segments 8 and 9 somewhat twisted, virtually making the antenna turns around its axis.

Alitrunk robust; prescutum with more or less distinct antero‑median carina; notauli shallow to deep and complete, with transversal costulae. Parapsidial furrows shaped as fine shining lines; parapsides more or less impressed behind, but each with sharp, raised postero‑lateral margin (hyaline in some species). Pres‑cutellum separated from scutellum by an impression or transverse row of punctures, or else middle part impressed and not distinct from scutellum; lateral wings of prescutellum with laterally marginate, pos‑teriorly pointed process or blunt hook‑like structure. Scutellum much narrower than prescutellum, form‑ing elongate near‑semicircle as seen from above, free borders marginate, but postero‑median portion con‑cave; posterior aspect broadly in an inverted Y‑ or U. Metanotum narrow, with blunt median tumosity. Propodeum with dorsal face flat, rectangular, steeply sloping posterad, separated from rectangular declivi‑tous face by transverse carina. As seen laterally, dorsal and declivitous faces of propodeum meeting at ob‑tuse angle; declivity marginate on each side.

Petiole clavate, with anterior peduncle and long, low, rounded node, usually bent slightly downward near base of posterior peduncle; spiracles papillose and prominent. Postpetiole broader than long in dor‑sal view and slightly broader posteriorly than anterad and broader than petiole; rounded above, sternum with shallow depression; attached to gaster by its full width. Gaster with first segment occupying most of its length; four visible apical segments subequal in length. Genital capsule slender; parameres slightly broadened, bluntly rounded and curved mesad at api‑ces, but tapered to a blunt end as seen laterally; vol‑sellae sock‑shaped, as usual in Myrmicinae; pygidium and subgenital segment unremarkable, with moder‑ately narrowly rounded apical margins.

Legs slender, tibiae of middle and hind pairs without apical spurs; tarsal claws slender and simple. Wings brownish, with opalescent bluish reflections. Forewing veined as in the gynes. Cross vein m‑cu absent, present as a spur from M, or as a complete crossvein. Hind wing with only two longitudinal tu‑bular veins issuing from median cell (apical abscissa of R and cu), with the tip of Sc branching off from fused Sc+R (Rf1 lacking). Anal loop (A+Cu‑a) short, without a spur of A, but as a folded line instead; 5‑9 submedian hamuli.

Larva (after Wheeler & Wheeler, 1954): Moderately stout; thorax and first two abdominal segments not constricted to form a long “neck”. Of the two types of denticulate hairs, the larger one has a fine, tapered, not hook‑liked apex.

PaP. avuls Zool. 47(2), 2007 35

revised key to Basiceros workers and gynes

1. Occipital margin of head rounded, forming a continuous or nearly continuous raised crest..........................2 Occipital margin of head trapezoidal or subrectangular, not forming a continuous crest ...............................32. In full‑face view, crest continuous around posterior part of vertex and separated from median convexity of

vertex by a broad, uninterrupted sulcus parallel to the crest .............................................................. B. militaris Crest medially emarginate and confluent at this point with median convexity of vertex ................... B. disciger3. Mandible subtriangular, strongly bent ventrally and with the outer borders straight basally; anepisternum

deeply depressed ...............................................................................................................................B. scambognathus Mandible triangular, not strongly bent ventrally, outer borders usually convex basally; mesopleura at the

same level as the surrounding surface ....................................................................................................................44. Head nearly as broad as long with the occipital lobes rounded; in frontal view, intermandibular space much

shorter than the half length of mandibles; gaster with few specialized hairs longer than the basal pilosity ..5 Head distinctly longer than broad with the occipital lobes angulated; in frontal view, intermandibular space

broad, with about half length of the mandibles; gaster densely covered with specialized hairs longer than the basal pilosity.........................................................................................................................................................6

5. Petiolar node and postpetiole totally covered with dense pilosity; petiolar node well developed and subrectan‑gular in dorsal view; ventral carina of petiole with many developed teeth of different shapes ..... B. conjugans

Petiolar node and postpetiole weakly covered with pilosity; petiolar node subcylindrical in dorsal view to almost obsolete; ventral carina of petiole with a single developed tooth at the anterior portion of pe‑duncle ...................................................................................................................................................... B. convexiceps

6. Basal portion of mandibles with dense pilosity formed by whitish squamiform hairs; ventral carina of peti‑ole with a short edge at the anterior portion of peduncle .................................................................B. singularis

Basal portion of mandibles smooth and shiny; ventral carina of petiole with a well developed edge at the anterior portion of peduncle, followed by smaller denticles of different shapes ..............................B. manni

scrobes with transversal rugulation over fine punc‑tuation; surface of head rugulose, the rugae forming a loose net with deep cells, with whole integument finely punctuated; lateral face of pronotum and ante‑rior coxae with gross punctuation, pronotal disc with punctuation and loose net of rugulae; mesopleuron, metapleuron, petiolar node, postpetiole and surface of the gaster feebly shining and rather smooth, with abundant punctures. Dorsum of head, laterobasal mandibular area, mesosomal dorsum, petiole, post‑petiole and first gastral sternite with small, whitish, subapressed and apressed spatulate hairs; hairs dense on head and antennal scapes, less abundant on me‑sosoma, waist and gaster; appendages with abundant cream‑colored subapressed spatulate hairs directed apically and becoming gradually finer towards tarsi; posterior part of head, dorsum of mesosoma, pos‑terolateral corner of pronotum, abdominal segments II‑VII with fairly abundant short, erect, strongly cla‑vate whitish‑golden hairs; distinct group of long fili‑form hairs project from labrum; pygidium with short erect hairs.

Head subtriangular. Mandible long and sub‑triangular; external margin of basal portion almost parallel; apical portion slightly longer than the basal one, external border strongly convergent with the

Basiceros scambognathus (brown) n. comb. (Figs. 1‑4)

Creightonidris scambognatha Brown, 1949:89. Holo‑type gyne, BRAZIL: Goiás, Campinas, x.1935 (Schwarzmeier) (MZSP) [examined]. Brown & Kempf, 1960:178, figs. 5, 8, 10 (genus revi‑sion, type locality); Kempf, 1972:80 (catalogue); Lattke, 1991:59 (record in Venezuela); Bolton, 1995a:1049 (census); Bolton, 1995b:146 (cata‑logue); Delabie, 2000:272 (distribution); Bolton, 2003:184 (synoptic classification); Castilho et al., in press. (distribution); new combination.

Meranoplus singularis Smith, 1858:195, pl. 13, figs. 6, 7 (only the gyne). Holotype gyne: BRAZIL: Ama‑zonas: Tefé (formerly known as Ega), no date, (no collector) [not examined].

Ceratobasis singularis Smith, 1860:78, pl. 4, figs. 12, 13 (only the gyne).

Worker: HW 1.13; HL 1.25, CI 92.31; ML 0.46; SL 0.96, SI 83.33; WL 1.52; HFL 1.30; TL 6.00. Color dark brown, appendages somewhat lighter; mesopleuron, petiolar peduncle and gaster with fer‑ruginous areas. Mandibles smooth and shining with minute scattered punctures; inner surface of antennal


FIgure 1: Basiceros scambognathus, worker; a) head in full‑face view; b) body in profile.

PaP. avuls Zool. 47(2), 2007 37

apex of the other mandible, and nearly straight mas‑ticatory border; apical portion almost perpendicularly bent ventrad at mid‑length; basal portion moderately convex in side view; a deep transverse‑oblique, con‑vex groove almost divides the basal mandibular disc in two, running from the masticatory margin to at least halfway across the mandible and ending shal‑lowly there, the grooves converging with the groove in the opposing mandible at the juncture of the two masticatory borders to form a broad V with an ob‑tuse, posteriorly directed, apex. Central disc of clyp‑eus convex, its anterior border very shallowly and broadly emarginate or concave; anterior portion of

head capsule deeply impressed compared with clyp‑eus, forming two transverse‑oblique grooves deeper anterad and meeting apically to form a broad inverted V. Triangular area indistinct, glabrous; no space be‑tween clypeus and mandibles when closed. Central portion of cephalic dorsum raised as large circular swelling with deep concavity in center forming thick ring. Posterior head margin with shallow and broad medial concavity; occipital lobes rounded and slightly projected. Eye relatively small (ca five facets at maxi‑mum diameter) and placed far back, just on the dorsal margin of antennal scrobe; scrobe deep, running full length of cephalic side; scape flattened and strongly

FIgure 2: B. scambognathus, gyne; a) head in full‑face view; b) body in profile; c) detail of the mandibular groove in full frontal view.


lobed basad by projection of anterior margin, api‑cal segment of funiculus longer than four preceding segments.

Mesosoma robust, promesonotum only moder‑ately convex dorsally; anepisternum set lower than the adjacent surface; metanotal groove deeply impressed;

propodeal spines very short and subtriangular; pro‑podeal spiracle wide open, relatively projected laterad and directed posteriorly.

Petiole pedunculate, slightly arched, with a prominent and thick node which is nearly longer than the peduncle, node with steep anterior and gen‑

FIgure 3: Basiceros scambognathus, male; a) head in full‑face view; b) body in profile.

PaP. avuls Zool. 47(2), 2007 39

tly sloping postero‑dorsal faces, peduncle ventrally carinate with a series of small, acute projected den‑ticles. Postpetiole subequal in length to the petiolar node, low in profile with a long, flat, sloping dorsal face which raises to a low rounded apex posteriorly and then drops slightly to its juncture with the gaster; seen from above, the petiole is narrower than postpe‑tiole and is oblong in shape, while the postpetiole is subtrapezoidal, as broad behind as long, the sides di‑verging posteriorly and then very slightly narrowed so that it is attached to gaster by nearly its entire breadth. Gaster long and oval, its anterior border semicircu‑larly excised to receive the postpetiole; first gastric segment forming the great bulk of the gaster.

Gyne: Holotype (n=3): HW 1.25 (1.16‑1.24); HL 1.42 (1.34‑1.42), CI 88 (87); ML 0.42 (0.39‑0.41) MI 30 (29); SL 1.09 (1.04‑1.09), SI 87 (88‑90); WL 1.84 (1.85‑1.88); HFL 1.30 (HFL 1.28‑1.31); TL 7.00 (6.93‑7.03). Like worker, with the modifications ex‑pected from myrmicine gynes. A complete description of the gyne was given by Brown (1949) in the original description of Creightonidris. Additional information is given above in the reviewed diagnosis of Basiceros.

Male: (n=4): HW 0.87‑1.00; HL 1.04‑1.15, CI 84‑87; ML 0.20‑0.23, MI (0.19‑0.20); WL 1.63‑1.87; HFL 1.23‑1.37. Color dark brown with somewhat ferruginous areas. Body sculpture basically rugose‑punctate, except for central discs of anepisternum and katepisternum which are smooth and shiny; head covered with scattered irregular rugae; alitrunk with sparse rugae on dorsal surface of promesonotum, in‑ferior portion of mesopleuron, propodeum and peti‑ole; broad punctures shallowly set on lateral surfaces of alitrunk and waist, but slightly finer on gaster. Long filiform whitish hairs cover body, densely arranged on head, dorsum of promesonotum and gaster.

Mandibles triangular, as broad as long, stout with 10 subconical teeth, the third and fourth ones broader than the others; apical tooth directed out‑wards and slightly distant from subapical one; exter‑nal margins of mandibles strongly convex at basal portion and straight to nearly concave towards apex. Head rounded in shape. Ocelli placed almost later‑ally in the median elevation of occipital border, cen‑tral ocellus preceded by deep cleft. A deep groove is present along posterior border of clypeus at space between eyes. Central disc of the clypeus raised and forming distinct circular area, lateral portions some‑what lower, anterior margin straight to slightly con‑cave. Eyes very large. Antennal scrobes shallow and limited posteriorly by high nucal carina.

In dorsal view, prescutum nearly as broad as long; notauli shallowly impressed; antero‑median portion of prescutum with a smooth and shining tri‑angular area; parapsidial furrows extending beyond prescutum mid‑length; parapsides broad and relative‑ly deep; prescutellum visible medially in dorsal view; lateral wings of prescutellum subtriangular, with acute and well developed postero‑lateral hook; scuto‑scutellar groove broad and deep with 2‑4 transversal rugae; scutellum twice as broad as long and divided by longitudinal groove medially. Propodeum bluntly angulated in side view, not bearing teeth or lamellae.

In lateral view, petiolar node subrectangular with rounded angles; in dorsal view node is rounded; subpetiolar spines varying from present and small to virtually absent. Postpetiole subtrapezoidal with pos‑terior border convex and broader than anterior one. Gaster long and oval.

comments

The aberrant mandible and depressed anepi‑sternum of Basiceros scambognathus separate this spe‑cies from the related Basiceros singularis. Originally, B. singularis was described by Smith (1860) based on a worker and a gyne. However, the gyne is a typical B. scambognathus, while the worker seems to be unre‑lated as judging from the figures (the type specimens are lost). This situation was only solved with the de‑scription of the genus Creightonidris by Brown in 1949, when he provided further details.

In the description of the holotype gyne, the val‑ue of TL is stated as being 7.4 mm; Brown & Kempf (1960) made an amendment to this measure stating that the specimen has the gaster dilated in around 0.4 mm; thus, the value here presented should be con‑sidered the correct measure.

A complete diagnosis of Basiceros was given by Brown & Kempf (1960) and Brown (1974). In the present paper we offer a supplement to the latter in order to include the features of B. scambognathus n. comb. We add information regarding the shape of the head and mandibles, and describe in more detail the structure of the gyne’s mesosoma.

All apomorphies of the Basicerotini defined by Bolton (2003) hold true for the specimens of B. scam-bognathus we examined.

Unfortunately we were aware of recent mate‑rial collected by colleagues only during the final revi‑sion process of the present paper. They were: a gyne collected at Nossa Senhora do Livramento county, northern Pantanal in Mato Grosso, Brasil, and the


worker collected in a secondary Atlantic Forest area in Lençóis, Bahia, Brasil (12°33’S 41°23’W) (Castilho et al. in press). Both specimens were obtained from leaf litter samples using Winklers extractors.

distribution

Until now, B. scambognathus was known only from the Brazilian largest biomes (Amazon Forest, Cerrado, and Atlantic Forest) and for a single locality in south Venezuela, near the border with Brazil (see map in Fig. 4). Its apparently discontinuous distribu‑tion and scattered records may reflect inappropriate

collecting techniques due to our ignorance of the spe‑cies biology.

biology

B. scambognathus is one of the most obscure taxa of neotropical ants and virtually nothing is known about its biology. Very few specimens are represented in the world’s ant collections, most of them are alate gynes and males, captured in widely spaced localities.

Brandão collected the first dealate B. scambog-nathus gyne in Uruaçú, Goiás state, in 1995, and at‑tempted to maintain it in artificial conditions in order

FIgure 4: Distribution map of Basiceros scambognathus.

PaP. avuls Zool. 47(2), 2007 41

to obtain workers or males and to record its behavior. Unfortunately, the specimen died some weeks after confinement and the only piece of information we were able to gather is that the captive gyne accepted termite workers as food in the laboratory. Interesting‑ly, this individual was found dead within the fungus garden of an Atta sexdens artificial nest in the same lab, so we can not rule out the possibility that B. scam-bognathus lives inside Atta nests (or another fungus grower ant), which could explain the difficulty to find this species in nature, and in part its status of rarity.

The second worker collected up to now was re‑covered alive along with other ants, several different terrestrial arthropods, and soil particles from a leaf litter sample. Once in a plastic recipient, the worker feigned death upon disturbance, in typical Basiceros style, remaining so for several minutes, and reassum‑ing movement quite slowly. Also as expected for a basicerotine ant, the body of the worker was tightly covered by a layer of dried soil (Hölldobler & Wilson, 1986). From the same sample we recovered also sev‑eral workers of an unidentified Apterostigma and many Blepharidatta conops workers.

Examined material: no locality, no date (no collector), [Gift from B. Bolton (BMNH) #59 74] (1 Gyne) (ANIC). BRASIL: Amapá: Amaparí, 8‑10.xi.1993 (W. França), [Tucano‑2] (1 Male) (INPA); (F.F. Ramos) (1 Male) (INPA); (N. Bittencourt) (1 Male) (INPA); 9‑10.xi.1993 (A. Pena) (1 Male) (INPA); 10‑14.xi.1993 (F.F. Ramos) (1 Male) (INPA). Amazonas: Estirão do Equador, Rio Javari, ix.1979 (Alvarenga) (1 Gyne, 1 Male) (MZSP); N of Manaus, Reserva Ducke, 22‑26.xi.1966 (no collector), [Malaise trap] (3 Males) (MZSP); 14.viii.1981 (C.B. Fairchild & J.A. Rafael), [Malaise] (1 Male) (INPA); 28.ix.1981 (J.A. Rafael), [Malaise] (1 Male) (INPA). Bahia: Maracás, Fazenda Maria Inácia, 24‑29.xi.1990 (Brandão; Diniz & Olivei‑ra) (1 Male) (MZSP). Goiás: Serra da Mesa, Colinas do Sul (14°01’S 48°12’W), 2‑15.xii.1995 (Silvestre; Di‑etz & Campaner), [Cerrado] (1 Male) (MZSP); Jataí, xii.1972 (F.M. Oliveira), [#8911] (1 Gyne) (MZSP). Maranhão: Estreito, Fazenda Itaueras (6°31’54”S 47°22’16”W), 12‑22.vi.2006 (R.R. Silva & R.M. Feito‑sa) (1 Worker) (MZSP). Mato Grosso: Sinop (12°31’S 55°37’W), x.1974 (M. Alvarenga), [#12306] (1 Gyne) (MZSP); [#12307] (6 Males) (MZSP); (Alvarenga & Roppa), [#12517] (1 Male) (MZSP); [#12551] (1 Gyne) (MZSP); [#12552] (4 Males) (MZSP); Vila Vera, x.1973 (M. Alvarenga), [#10253] (6 Males) (MZSP). Pará: Santarém Novo, Fazenda Jaburu, 7‑9.i.1993 (J. Dias) (1 Male) (INPA); Igarapé‑Açú, i.1949 (Gonçalves) (1 Gyne) (MCZC). Rondônia: 62 km

S of Ariquemes, Fazenda Rancho Grande (10°32’S 62°48’W), 12‑22.xi.1991 (E.M. Fisher) (3 Males) (PWRD). Roraima: Ilha de Maracá, Rio Uraricoera, 18‑28.viii.1987 (J.A. Rafael et al.) (1 Male) (INPA).

resuMo

No presente trabalho, propomos a sinonimia do gênero mo-notípico neotropical de formigas mirmicíneas (Basicerotini) Creightonidris Brown sob Basiceros Schulz e descrevemos pela primeira vez a operária e o macho de Basiceros scam‑bognathus comb. n., conhecida até agora somente por rainhas aladas. Apresentamos dados sobre a distribuição dessa espécie, uma nova diagnose para Basiceros e uma chave atualizada para identificação de operárias e gines do gênero. Os poucos dados conhecidos sobre a biologia de B. scambognathus são sumarizados.

Palavras-chave: formigas, Basicerotini, Creightonidris, Basiceros, chave, sinonímia, descrição de operária e macho.

AcknowledgMents

The authors would like to thank Dr. Phillip Ward for the loan of important material. The au‑thor RMF and Dr. Rogério Rosa da Silva collected the worker of B. scambognathus in an expedition sup‑ported by OIKOS Pesquisa Aplicada Ltda; we would like to make a special reference to Dr. Fábio Olmos and Dr. José Fernando Pacheco. Dr. Nelson Papavero and Dr. Ubirajara Martins helped with the nomencla‑ture. Lara M. Guimarães took the SEM images and Gláucia Marconato made the worker habitus drawing. We would also like to thank several individuals and institutions that helped or supported our collecting trips. The present work was supported in part by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). John Longino and an anony‑mous reviewer suggested several significant improve‑ments to the manuscript.

reFerences

baroni urbani, c. & de andrade, M.l. 1994. First description of fossil Dacetini ants with a critical analysis of the current classification of the tribe (Amber collection Stuttgart: Hymenoptera, Formicidae. VI: Dacetini). Stuttgarter Beiträge zur Naturkunde, Serie B Geologie und Paläontologie, 198:1‑65.

bolton, b. 1995a. A New General catalogue of the Ants of the Word. Harvard University Press, Cambridge, Massachusetts, 504p.


bolton, b. 1995b. A taxonomic and zoogeographical census of the extant ant taxa. Journal of Natural History, 29:1037‑1056.

bolton, b. 1998. Monophyly of the dacetonine tribe‑group and its component tribes (Hymenoptera: Formicidae). Bulletin of the Natural History Museum London, Entomology, 67(1):65‑78.

bolton, b. 2003. Synopsis and Classification of Formicidae. Memoirs of the American Entomological Institute, 71:1‑370.

brown Jr., w.l. 1949. Revision of the ant tribe Dacetini: IV. Some genera properly excluded from the Dacetini, with the establishment of the Basicerotini, new tribe. Transactions of the American Entomological Society, 75:83‑96.

brown Jr., w.l. & KeMPF, w.w. 1960. A world revision of the ant tribe Basicerotini. Studia Entomologica, 3:161‑250.

brown Jr., w.l. 1974. A supplement to the revision of the ant genus Basiceros. Journal of the New York Entomological Society, 82:131‑140.

castilho, a.c.c.; delabie, J.h.c.; Marques, M.i.; adis, J. & Mendes, l.F. In press. Registros novos da formiga criptobiótica Creightonidris scambognatha Brown (Hymenoptera, Formicidae). Neotropical Entomology.

de andrade, M.l. & baroni urbani, c. 1999. Diversity and adaptation in the ant genus Cephalotes, past and present. Stuttgarter Beiträge zur Naturkunde, Serie B Geologie und Paläontologie, 271:1‑889.

delabie, J.h. 2000. Creightonidris scambognatha (Hymenoptera: Formicidae: Basicerotini) in the Atlantic forest biome, east of Bahia, Brazil. Revista de Biologia Tropical, 48:272‑273.

dietZ, b.h. 2004. Revisão sistemática da tribo Basicerotini (Hymenoptera: Myrmicinae). Universidade de São Paulo, São Paulo, Brazil. (Ph. D. Thesis), 245p.

hölldobler, b. & wilson, e.o. 1986. Soil‑binding pilosity and camouflage in ants of the tribes Basicerotini and Stegomyrmecini. Zoomorphology, 106:12‑20.

hölldobler, b. & wilson, e.o. 1990. The Ants. Belknap Press of the Harvard University Press, Cambridge, Massachusetts.

KeMPF, w.w. 1972. Catálogo abreviado das formigas da Região Neotropical. Studia Entomologica, N.S., 10:353‑360.

lattKe, J.e. 1991. Estudios de hormigas de Venezuela (Hymenoptera: Formicidae). Boletín de Entomología Venezolana, 6:57‑61.

sMith, F. 1858. Catalogue of Hymenopterous Insects in the Collection of the British Museum, 6 Formicidae. British Museum, London, 216p.

sMith, F. 1860. Descriptions of new genera and species of exotic Hymenoptera. Journal of Entomology, 1:65‑84.

weber, n.a. 1950. New Trinidad Myrmicinae, with a note on Basiceros Schulz (Hymenoptera, Formicidae). American Museum Novitates, 1465:1‑6.

wheeler, G.c. & wheeler, J. 1954. The ant larvae of the myrmicine tribes Basicerotini and Dacetini. Psyche, 61:112‑113.

Recebido em: 26.11.2006 Aceito em: 16.02.2007

Impresso em: 15.06.2007

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